Mapping Environmental Partitioning Properties of Nonpolar Complex Mixtures by Use of GC × GC

Abstract

Comprehensive two-dimensional gas chromatography (GC × GC) is effective for separating and quantifying nonpolar organic chemicals in complex mixtures. Here we present a model to estimate 11 environmental partitioning properties for nonpolar analytes based on GC × GC chromatogram retention time information. The considered partitioning properties span several phases including pure liquid, air, water, octanol, hexadecane, particle natural organic matter, dissolved organic matter, and organism lipids. The model training set and test sets are based on a literature compilation of 648 individual experimental partitioning property data. For a test set of 50 nonpolar environmental contaminants, predicted partition coefficients exhibit root-mean-squared errors ranging from 0.19 to 0.48 log unit, outperforming Abraham-type solvation models for the same chemical set. The approach is applicable to nonpolar organic chemicals containing C, H, F, Cl, Br, and I, having boiling points ≤402 °C. The presented model is calibrated, easy to apply, and requires the user only to identify a small set of known analytes that adapt the model to the GC × GC instrument program. The analyst can thus map partitioning property estimates onto GC × GC chromatograms of complex mixtures. For example, analyzed nonpolar chemicals can be screened for long-range transport potential, aquatic bioaccumulation potential, arctic contamination potential, and other characteristic partitioning behaviors.

Development and Evaluation of Two-Parameter Linear Free Energy Models for the Prediction of Human Skin Permeability Coefficient of Neutral Organic Chemicals

“…We excluded ionized species from this data because our proposed models, PPM and GC×GC model, can theoretically account for the intermolecular interactions for neutral organic chemicals only. This resulted into a data size of 175 neutral organic chemicals, and is shown in For the GC×GC model, a two-parameter LFER equation was calibrated using retention parameters ( 1 , 2 ) that were estimated for a set of 79 model nonpolar chemicals following the approach developed elsewhere 26,27 . The model training set (Table S3) is formulated to span several nonpolar families in a balanced way.…”

“…The model training set (Table S3) is formulated to span several nonpolar families in a balanced way. Then, the GC×GC model was validated independently using a set of 52 nonpolar chemicals (Table S4), which were analyzed on the GC×GC instrument in previous studies 26,27 . The experimental values of for the nonpolar chemicals in the training and validation sets for the GC×GC model were not available.…”

“…retention parameters, 1 and 2By the virtue of equation 7, analysts can overlay the estimates of skin permeability coefficients on the GC×GC chromatograms of complex mixtures of nonpolar chemicals __ akin to cases shown previously for the GC×GC chromatogram of polychlorinated alkane mixtures having several thousand congeners 26,27. …”

Development and Evaluation of Two-Parameter Linear Free Energy Models for the Prediction of Human Skin Permeability Coefficient of Neutral Organic Chemicals

“…Scientists were able to identify known skin penetrants in environmental samples such as the household dust using comprehensive two-dimensional liquid chromatography coupled with time-of-flight mass spectrometry 25 . In addition to its separation power, recent studies 26,27,28 demonstrated the potential of GC×GC in chemical risk assessment.…”

Inlet backflushing device for the improvement of comprehensive two dimensional gas chromatographic separations

“…GC × GC is considered an established separation technique and for the last decade focus has shifted away from the development of modulation technology to applying the technique to an ever increasing number of analytical challenges. Fields in which GC × GC applications are popular include petroleum and petrochemicals [6][7][8][9][10][11][12][13][14][15][16]; food, flavours and fragrances [17][18][19][20][21][22][23][24][25][26][27][28][29][30]; metabolomics [31][32][33][34][35][36][37][38][39][40][41][42] and environmental analysis [43][44][45][46][47][48][49]. Although GC × GC has never been more widespread, there are some applications that remain challenging for a chromatographer to perfect.…”